Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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COUNTER-ROTATING VORTICES GENERATOR FOR AN AIRCRAFT WING
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to a wing lift device for
increasing the lift capability of aircraft wings.
Description of the Prior Art
Lift of an airplane wing is a function of its forward
speed and angle of attack. For each type of wing there is an
upper limit to the angle of attack that can be effectively
reached, beyond which a stall suddenly occurs with almost total
loss of lift. The separation of the boundary layer from the
surface of the aircraft wing occurs at a point on the surface of
the wing at increasingly forward points from the trailing edge
thereof as the angle of attack is increased. Therefore, in order
to accommodate larger and heavier aircraft, it is necessary that
progressively higher takeoff and landing velocities be maintained
in order to prevent stall of the wing and the loss of lift cap-
ability. It would be advantageous, therefore, to increase the
lift capability of aircraft wings by more efficiently utilizing
the airflow across the top surface of the wing.
SUMMARY OF THE INVENTION
The invention in its broader aspect pertains to
apparatus for increasing the lift generated by an aircraft wing,
having upper and lower surfaces, while propelled through a fluid
medium. The apparatus comprises a finger mounted adjacent to
the leading edge of the wing and extending forwardly therefrom
such that the finger is essentially tangential to the upper
surface of the wing, the finger having lateral edges thereon.
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The finger is mounted on the wing such that as the wing is
propelled through the fluid medium impingement of the fluid
medium on the finger produces, by flow around the lateral edges,
a first and second vortex trailing rearwardly from the finger
over the upper surface of the wing in the direction of fluid
flow, each of the vortices being in contact with and counter-
rotating with respect to the other. The finger is sized such
that each vortex produced thereby is of sufficient size and
strength to modify the flow pattern above the boundary layer
on the wing upper surface so as to effect an increase in the
lift.
More particularly, the invention relates to, in
combination to an aircraft wing, a wing lift device including
at least one, but preferably a plurality of laterally spaced, for-
wardly extending finger members mounted adjacent to the forward
edge of the airfoil. The fingers may be mounted directly on the
airfoil or supported a predetermined distance thereabove by suit-
able struts or the like. The forwardly extending fingers obstruct
the airflow impinging thereon at predetermined angles of attack so
as to generate counter-rotating vortices trailing backwardly
therefrom over substantially the entire upper surface of the
wing that lies behind the fingers as the airflow moves upwardly
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and over the lateral edges of thc fingcrs. Thc rin~ers ~re
sized and configured such that the counter-rotating vorticcs
produced thereby are in contact one with the other and remain
intact as vortices as they extend backwardly and trail over the
upper surface of the aircraft wing. As a result of the counter-
rotating vortices, a blockage effect is created which modifies
the airflow patterns across the upper surface of the wing and to
produce increased lift capability o~ tl-e Will'1~
BRIEF DESCRIPTION OF TIIE DR~WINGS
The invention will be more fully understood from the
following detailed description of a preferred embodiment
thereof, taken in connection with the accompanying drawings,
which form a part of the specification, and in which:
Figure 1 is a plan view of an aircraft wing
illustrating a wing lift device embodyinq the teachings of this
invention;
Figure 2 is a front view taken along lines 2 - 2 of
Figure l;
Figure 3 is a section view of the wing of Fiyure l;
Figure 4 is an isolated perspective view of one
embodiment of a wing lift device in accordance with the
teachings of the invention;
Figure 5 is a fragmentary view of an alternate mode of
attachment of the wincr lift device to an aircraft wing;
Figures 6, 7, 8, 9, 10, 11 and 12 are alternate
embodiments of the invention.
_ESCRIPTION OF THF PREFERRED EMBODIMENT
Throughout the following description, similar
reference numerals refer to similar elements in all figures of
the drawings.
Referring to Figures 1 through 3, an aircraft wing,
generally indicated by reference numeral 10, of known airfoil
configuration as viewed in the cross section of Figure 3 is
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shown in isolation from the remainder oE the aircraft fusclagc
and like structures with which it is normally associated. It is
understood that the wing 10 may be either a conventional
straight wing or a swept-back wing and still be utilizable in
connection with a wing lift device generally indicated by
reference numeral 12 embodying the teachings of this invention.
The wing 10 includes a forward or leading edge 14 and
a rearward or trailing edge 16. An upper surface 18 and a lower
surface 20 are interposed to connect the forward and rearward
edges 14 and 16, respectively. The width C of the wing 10 is
the distance between the leading edge 14 and trailing edge 16 of
the wing 10. For definitional purposes, the wing 10 will be
assumed to be confronted by an airflow indicated by a vector 22
approaching the leading edge 14 of the wing 10 f LOm t~le lower
forward direction defining a predetermined angle of attack 24
with respect to a horizontal datum.
Mounted adjacent to the leading edge 14 of the wing 10
is at least one, but preferably a plurality, of la-terally
spaced, forwardly extending finger members 30. As viewed in the
figures, the fingers 30 are provided with a forward and trailing
edge 32 and 34, respectively, and are also provided with upper
surfaces 36 and lower surfaces 38. The upper and lower surfaces
36 and 38 meet at lateral edges 40A and 40B. As is discussed
more fully herein, the fingers 30 define a predetermined cross
sectional area when viewed as along section lines 2 - 2 in
Figure 1. As shown in Figures 2 and 4, the fingers 30 are
preferably biconve:; in cross section. The fi~ cl-s 8n may bc
mounted directly to the upper surface 18 of the wing 10 adjacent
the leading edge 14 thereof (as illustrated in Figure 2) or,
alternatively, as illustrated in Figure 5, may be mounted a
predetermined distance H thereabove on suitable struts 42 or the
like. The fingers 30 may be pivotally mounted, if desired.
By whatever mode of attachment utilized, the fingers
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are spaced latercally a predc~cL-millcd di;~all(c ~, bci~c(~ll r
centerlines of adjacent fingers 30. sy spaced lateral adjacency
it is meant that adjacent finyers 30 are close enou~h together
that adjacent vortices are in contact with each other.
Referring to Figure 4, it is seen that each finger 30 has a
predetermined length 1, (measured along the forwardly projecting
direction of the fingers), width w, (measured in a direction
transverse to the forward direction), and heiallt h, definc(1 in
accordance with Figure 4. It will be appreciated that the
forward dimension 1 of the finger is at least equal to but
preferably greater than its transverse dimension w as
illustrated in Figure 4. In practical application, each
aircraft wing will have appropriately configured and
dimensioned fingers 30 for generating counter-rotating vortices
of sufficient size and strength to remain intact until thcy
reach substantially to or past the trailing cdge of Lll(~ willg.
That is to say, the fingers 30 are configured, dimensioned and
mounted on the wing so as to generate a pair of counter-
rotating, contacting vortices which are strong enough to remain
intact and not dissipate over substantially the width of or the
entire width of the wing behind the finaers. Bv way of examplc,
suitable values for finger dimensions, in terms of the width of
the wing C include: projection of the finger 30 forward of the
edge 14 of the wing (distance 43, Fiaure 1), .29C; width w of
finger, .167C; spacing L between fingers 30, .333C.
The fingers 30 may exhibit any of a predetermined
plurality of configurations, as illustrated in Figures 6, 7, 8,
9, 10 and 11. The fingers 30 may cithcL^ bc ul~wal-dlv (~ .'.l, as
viewed from the side as shown in Figure 6, downwardly curved as
viewed from the side as shown in Figure 7, or may be T-shaped in
cross section as viewed from the frontal view shown in Figure 8.
Further, as viewed in plan, the fingers 30 may be trapezoidal,
with the short base extending forward of the edge 14 (Figure 9)
or the long base forward of the edge i4 (~igures '0 and 11~
Further, the sides of the trapezoid may be straight (~igure 10),
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serrated (Figure 9) or curved (~i.gure 11), whetiler the short or
long base is forwardly extending. The fingers, when viewed in
plan, may also be triangular in -Eorm.
As mentioned, suitable means may be provided for
extending the fingers 30 to their forwardly extending position
adjacent the leading edge 14 of the wing 10, and retracting the
fingers into a recess provided withill the WillCl (not showll), or
disposing the finger 30 to any intermediate position
therebetween. Furthermore, as viewed in Fiqure 5, the fingers
30 may be pivotally mounted, as at 44, with the points of
attachment of the finger 30 to the strut 92, or between thc
strut 42 and the surface 18 of the wing 10, so as to be moveable
either upwardly or downwardly, lateral.lv from siAe-to-side, or
both, as may be necessary in certain situations. Suitable means
for con-trolling the upward or downward lateral. movelnellt of the
fingers may be provided.
In operation, the wing lift clevice l2, incluAing the
fingers 30, has the effect of changing the airflow patterns with
respect to the upper surface 18 of the wing 10. This is
believed to be an effect of a counter-rotati.ng vortcx system
(Figures 1 and 2) trailing rearwardly from the fingers 30. As
the airflow vector 22 impinges on the lower surfaces 38 of the
fingers 30, the flow moves upwardly and around the lateral edges
40A and 40B of the fingers 30 to qenerate side-by-side counter-
rotating vortices 50A and 50B (illustrated diagrammatically in
Figures 1 and 2). By "counter-rotating vortices" it is meant
that the pair of vortices 50A all~ 50s producecl frolll eacll fill-lel-
30 are close enough toaether as to be in contact with and
reinforce the other as they trail rearwardly in oppositely
rotating directions across the surface of the wing behind the
fingers. As seen from the front (Figure 2), the vortex 50A
rotates in a clockwise direction as it trails rearwardly over
the upper surface 18 of the wing 10. The vortex 50B rotates in
a counterclockwisc? dirccti.on as it tL-ai~s re~ wal ~ly O\'CI- tlle
upper surface 18 of the wing 10.
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A consequence of the counter-rotatiny vortices is that
the lift capability of the winy 10 is increased for a yiven
angle of attack and air speed. Alternatively, decreased angles
of attack or lower air speeds would be required to maintain the
lift capability of the wing at a predetermined value. As a
result takeoffs and landings at slower speeds and with shorter
runways may be accomplished through the utilization of the wing
lift device embodying the teachings of this invention.
Each of the projecting fingers 30 generate the
counter-rotating vortices 50A~and 50B, as discussed above,-
covering the upper surface 18 behind the fingers. As these
vortices trail rearwardly over the top surface 18 of the wing, a
possible mode of action is that these vortices 50 induce chan~es
in the alrflow pattern over the surface 18 of the wing that
extend considerably above the thickness dimension 52 (Fiyure 2)
of the vortices 50. It is believed that the vortices 50 induce
a second set of vortices above them which together create a
blockage effect above the wing surface 18. As a result, the
airflow over the upper surface 18 "humps" over the wing as if
the wing curvature were greater than it actually is.
Consequently, increased lift is generated from the wing. It is
also noted that airflow over the upper surface 18 of the wing do
not sweep forwardly over the wing (the characteristic of the
stall condition) until high angles of attack well past the usual
stall region are attained. The finaers 30 projectinq forwardly
from the wing 10 yenerate increased lift from the winq over a
wide range from very low angles of attack, (wh~re there is no
stall even with conventional wings), through angles of attack in
the usual stall region, to relatively high angles of attack. As
will be evident from Fiqures 1 to 3, for example, when the
fingers 30 are directly attached to the leading edge of the
wing, they are each tangentially mounted with respect to the
wing's surface adjacent the leading edge. It will be
appreciated that the arrangement of the fingers, their
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angularity and location, although generatina the counter-
rotatinq vortices, should not otherwise obstruct airflow over
the wing surface 18. The fingers 30 are not intended and should
be positioned and mounted on the leading edge to generate the
counter-rotating vortices ancl ~ct not provic1e a s~oilcl c 1- rcc~ .
When the fingers are located above the wing (as in Figures 5 and
8), the space between the wing and the finger disposed
thereabove allows a continuous airflow over the winq's surface
to occur. Accordingly when the fingers 30 are attached directly
to the leading edge of the wing, the fingers should be arranged
to provide a smooth continuous airflow over the upper
surface subject to the counter-rotating vorticcs and thus the
trailing edge 34 of fingers 30 would in practice be smoothly
aligned with or connected to the surface of the wing. The same
would of course be the case where the wings are pivotally or
retractably mounted. By "continuous airflow" it is meant that
the fingers should be positioned so as to only generate the
desired counter-rotating vortices and not provide a spoilel-
effect.
As seen from Figure 12, the fingers 30 may be used
adjacent the leading edge 14' of a swept back wing 10'. The
fingers 30 have, if necessary, the leading edges 32' thereof
angled along a common plane, as illustrated in Figure 12 to
prevent mutual interference. The angled leading edges 32' may
or may not be e~tended parallel to the leadillg edgc 14' of thc
swept back wing.
Having described a preferred embodiment of the
invention, those skilled in the art may effect modifications
thereto in view of the teachings herein provided. Yet, it is
understood that these modifications are within the contemplation
of this invention, as defined in the appended claims.
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Supplementary Disclosure
In the principal disclosure it was indicated that
fingers 30 may be pivotally mounted, as exemplified at 44 in
Figure 5, so as to be moveable either upwardly or downwardly,
laterally in a side-to-side, or botll, as ma~ be lleCe5S;II'~' 01-
desirable in certain situations. Suitable means for controlling
the upward, downward and/or lateral movement would be provided.
Similarly, it was disclosed in the principal disclosure, that
suitable means may be provided for extendinq fingers 30
forwardly from a recess (not shown) to their forwardly extending
position adjacent the leading edqe 14 of the wing 10 and for
retracting the fingers into the recess.
Although various means of pivotally mounting the
fingers are possible, it can be done by setting them in a
gimbal mounting with vertical and transverse axes to allow for
side-to-side and up-and-down rotational motions, respectively.
Rotations about other axes can be used. The motions can be
accomplished by means of a lever arm e~te~ from e.lcll .~
at the end of which is a nut through which a threaded bolt is
passed to form a jackscrew. An electric or hydraulic motor can
be used to power the jackscrew. This mechanism allows the
fingers to be positioned in any attitude and to be held rigidly
in that attitude. It will be appreciated that once an attitude
of the finger is selected, the fingers are to remain rigidly and
securely in place.
An alternative mechanism would include a linear
actuator to move the lever arms, with detents and an appropriate
latching device such as a pin to fit the detent, the detents
being located to obtain the best average position for two, or
perhaps more, flight conditions. The actuator can be
electrically or hydraulically powered. It is appreciated that
any suitable means may be utilized to mount the fingers, move
them in side-to-side and in up-and-down rotational motions, and
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rigidly secure them in a selected attitude in accordance with
the invention.
Similarly for extendina or retracting the fingers, the
fingers may be moun-ted on guides to allow slidillg motioll, and
either a jackscrew or a linear actuator with detents used to
power the motion. A ~imbal system as described above can be
included with the fingers mounted on the guides to
simultaneously provide rotational motion.
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